Table 2.

Association between breast density and risk in the overall, screen-detected, and interval cancer populations

Cases (n)Controls (n)OR*P95% CI
Overall population
    Wolfe's patterns
        N11164651 (reference)
        P11374551.160.3160.87-1.54
        P22967801.480.0021.15-1.89
        DY851801.790.0011.27-2.52
        P for trend1.22<0.001
    Visual percent density
        0-15%1806741 (reference)
        20-35%1003531.000.9790.76-1.33
        40-65%1604641.240.0890.97-1.59
        70-90%1943891.81<0.0011.41-2.32
        P for trend1.21<0.001
        Mean density, % (SD)42.8 (28.6)35.9 (27.9)
    Interactive threshold
        0.00-9.41%1125171 (reference)
        9.43-22.92%1444841.370.0291.03-1.82
        22.94-37.03%1714581.80<0.0011.36-2.37
        37.04-84.74%2074212.45<0.0011.86-3.23
        P for trend1.34<0.001
        Mean density, % (SD)29.3 (19.2)23.8 (17.9)
    SMF
        11.5-19.1%1375001 (reference)
        19.2-22.7%1424921.110.4480.85-1.46
        22.8-28.2%1554611.310.0541.00-1.71
        28.3-59.3%2004271.92<0.0011.47-2.51
        P for trend1.24<0.001
        Mean density, % (SD)25.6 (8.0)24.0 (7.1)
Screen-detected cancer population
    Wolfe's patterns
        N1922951 (reference)
        P11033041.040.8280.75-1.44
        P21865281.080.6140.80-1.45
        DY471281.140.5480.75-1.73
        P for trend1.040.502
    Visual percent density
        0-15%1424351 (reference)
        20-30%612090.810.2370.57-1.15
        35-60%1053110.970.8590.72-1.31
        65-90%1203001.180.2770.88-1.58
        P for trend1.060.266
        Mean density, % (SD)38.5 (28.0)36.6 (27.6)
    Interactive threshold
        0.00-9.34%913301 (reference)
        9.35-22.72%1073141.230.2220.88-1.70
        22.73-36.13%1123091.340.0790.97-1.86
        36.25-84.74%1183021.560.0071.13-2.17
        P for trend1.150.007
        Mean density, % (SD)26.2 (18.3)24.3 (18.1)
    SMF
        11.5-19.0%1113231 (reference)
        19.1-22.5%943150.900.5330.65-1.25
        22.6-28.1%1053161.030.8650.75-1.41
        28.2-59.3%1183011.230.1940.90-1.69
        P for trend1.080.143
        Mean density, % (SD)24.8 (8.1)24.2 (7.2)
Interval cancer population
    Wolfe's patterns
        N1241701 (reference)
        P1341511.550.1340.87-2.77
        P21102523.11<0.0011.90-5.10
        DY38524.80<0.0012.58-8.93
        P for trend1.74<0.001
    Visual percent density
        0-15%382391 (reference)
        20-35%261201.400.2400.80-2.43
        40-70%821752.99<0.0011.93-4.55
        75-90%60914.07<0.0012.48-6.70
        P for trend1.65
        Mean density, % (SD)51.8 (27.7)34.5 (28.3)
    Interactive threshold
        0.00-9.75%201881 (reference)
        9.76-23.62%391692.300.0061.28-4.16
        23.63-38.52%601484.14<0.0012.35-7.29
        38.63-82.28%871207.31<0.0014.17-12.8
        P for trend1.89<0.001
        Mean density, % (SD)35.7 (19.7)22.3 (17.6)
    SMF
        11.6-19.4%261821 (reference)
        19.5-22.8%461622.220.0041.28-3.82
        22.9-28.4%521572.540.0011.49-4.36
        28.5-55.6%821245.77<0.0013.40-9.79
        P for trend1.71<0.001
    Mean density, % (SD)27.2 (7.5)23.6 (6.8)
  • * Adjusted for age, mode of diagnosis, and screening center.

  • ORs for every increase in respective density quartiles or categories (Wolfe's patterns).